Carton lock construction

ABSTRACT

A carton lock construction is provided for releasably securing a cover in a closed overlying relation with respect to the open top of a tray. One lock component of the carton includes a flap hingedly connected to the upper edge of the tray delimiting the open top thereof. The flap, when in a locking position, assumes an upright position disposed in telescoping relation behind a depending wall of the closed cover. The flap is provided at its lateral end limits with substantially flat inwardly projecting locking ledges. The ledges are provided with broad substantially flat surfaces which are located intermediate the flap hinge and the upper elongated edge of the flap. The cover depending wall is provided with a pair of inwardly projecting protuberances which engage the corresponding flap locking ledges and retain the cover in its closed position.

lllloyd et ah ii ehl 2% [54} iCAtRTCUJN lls iltfilli CQNSTRUQTHQW [72] inventors: James W. lEoyd, Crown loint, ind; Clitiord llil. lilleseett, South Holland, Ill.

[73] Assignee: Packaging Corporation at America, Evanston, ill.

[22] Filed: June 3, i974) 21 App]. No; Anew Primary Examiner-Edward A. Sroka Assistant Examiner-H. S. Lane Attorney-Pendleton, Neuman, Williams 8: Anderson A carton lock construction is provided for releasably securing a cover in a closed overlying relation with respect to the open top of a tray. One lock component of the carton includes a flap hingedly connected to the upper edge of the tray delimiting the open top thereof. The flap, when in a locking position, assumes an upright position disposed in telescoping relation behind 2 depending wall of the closed cover. The flap is provided at its lateral end limits with substantially lat inwardly projecting locking ledges. The ledges are provided with broad substantially flat surfaces which are located intermediate the flap hinge and the upper elongated edge of the flap. The co /er depending wall is provided with a pair of inwardly projecting protuberances which engage the corresponding flap locking ledges and retain the cover in its closed position.

7 Claims, 6 Drawing Figures in commercial egg-paclcaging plants, the loading and closing of egg cartons is customarily an expeditious, automatic mechanical operation. For this reason, therefore, the cartons must be of a simple, yet sturdy, construction, capable of withstanding abrupt mechanical manipulations, and afford effective protection for the accommodated eggs. Subsequent to the cartons being loaded and closed, they are normally paclred in corrugated shipping containers holding 30 dozen eggs for either shipment directly to the customer or held in cold storage for subsequent delivery. in either case, the closed, loaded ctrtons are oftentimes subjected to rigorous handling during which time the carton may become susceptible to accidental opening. in addition to being able to withstand such rigorous handling during initial loading and closing, the carton must also be capable of being repeatedly opened and closed in a facile manner by the housewife without damage to the contents. With numerous prior egg carton locl: constructions the eggs disposed in the cells adjacent the loclr resist inward movement of the locking flap during locking and unlocking of the cover and thus, materially increase the incidents of breakage of said adjacent eggs. Furthermore, in many cartons, particularly when formed of molded pulp, the cartons become warped or distorted when subjected to intense drying tem' peratures during formation, or when exposed to a high humidity condition, with the result that proper alignment of the locking components sometimes becomes difficult to achieve or to maintain thereby impairing the effectiveness of the lock. in addition to the foregoing, the cartons must be easy and inexpensive to produce.

Thus, it is an object of this invention to provide a carton and loclt therefor which is of simple and inexpensive construction, is capable of providing effective protection for its contents even though the loaded carton is subjected to rigorous handling, maybe readily loaded and closed either manually or by automatic mechanical equipment, and provides a secure loclr even though the carton is subjected to severe climatic conditions.

it is a further object oi this invention to provide a carton and loclt therefor wherein the lock is capable of repeated opening and closing without interfering with or damaging the carton contents.

it is a still further object of this invention to provide carton and lock therefor wherein the carton may be formed of a variety of inexpensive materials without impairing the security of the lock.

Further and additional objects will appear from the description, accompanying drawings and appended claims.

in accordance with one embodiment of the invention, a carton is provided which includes a tray having an open top and a cover which is adapted to overlie the tray and close off the open top thereof. A lock is provided for retaining the cover in a closed position. The lock includes a lisp which is hingedly connected to a portion of the tray delimiting the open top thereof. 'l'he flap is adapted to assume an upright locking position wherein it is in telescoping relation behind a depending wall of die closed cover. Formed in the flap and adjacent oppositc lateral ends thereof are substantially flat, broad, inwardly projecting locking ledge surfaces. Disposed in vertical alignment with the locking ledges are inwardly projecting abutments which are adapted to engage adjacent marginal portions of the tray open top and retain the flap in its upright locking position. Cooperating with the loclting ledge surfaces are inwardly extending protuberances carried by the cover depending wall. Each protuberance has the upper limits thereof extending abruptly inwardly into the carton so to lockingly engage the adjacent locking ledge surface when the cover is in its fully closed position.

DESClilPl'lUN For a more complete understanding or the invention reference should be made to the drawings wherein:

FIG. it is a perspective top end view or a loa fully opened condition and embodying one proved loch.

PEG. 2 is a perspective from view oi. the carton oi hilt ii and showing the flap in its upright loclring position.

FlG. 3 is similar to FIG. E, but showing the cover about to assume its closed position.

FlG. d is an enlarged vertical sectional view taken along line ld of Phil. 5.

H 6. 5 is a fragmentary perspective bottom view ton of HG. d and showing the cover thereof in .ui position.

FlG. s is a fragmentary perspective from: view at a which embodies a modified loch, but showing the llap thereof in its upright locking position and the cover in a fully open position.

Referring now to the drawings and more particulariy to PM l, a carton illl is shown which is adapted to accommodate a plurality of fragile articles such as a dozen The carton illl, as illustrated, is formed of molded pulp and is cornn'ionly referred to as a 2X6 egg carton; however, the improved lock to be hereinafter described may be utilized on various other types of cartons and may be formed by pulp molding, their-- moforming, and/or injection molding. Other materials besides paper pulp, such as expanded polystyrene, polyethylene, etc. may be used for forming the carton.

Carton llll includes an elongated tray section -i having formed therein a plurality of egg-accomoduting cell" llo-f and liIZn-f which are arranged in two parallel rov of sin cells each. The open top of the tray section is delimited by an outwardly projecting peripheral flange Connected by hingeline l9 to the rear elongated edge of flange l3 is a cover section l lingcdly connected to the opposite or front elongated edge of flange is a inching llap Cover section lid includes atop panel in which is delimited by depending outwardly flared front Il'l', rear ill, and end Jill walls. The lower edges of the cover walls form an outwardly projecting peripheral flange 2i which, except for a recessed front portion Illa thereof, is adapted to engage the flange 13 of the tray section when the cover is in its fully closed position.

The top panel lb or" the cover section in the illustrated embodiment includes a centrally disposed depending post lll'na which is adapted to abut an upwardly projecting centrally disposed post T formed in the tray section intermediate the rows of cells. The abutting posts enhance materially the loadbearing strength of the carton. A hollow transversely extend ing reenforcing rib lob interconnects the sides oi the post lbs with the from i? and rear l3 walls of the cover section.

Loclring flap lid has formed at opposite ends thereof locking ledges l, which are disposed intermediate the flap hinge-line 22 and the upper elongated. edge lilo oi the flap, firs in FlG. 4, each ledge L comprises a broad substantially flat surface which extends abruptly inwardly into the carton and cooperates with the portion Mb of the flap between the ledge L and edge 15a to form an included angle l-i of approximately Disposed beneath and in substantial vertical alignment with each ledge L is an inwardly projecting abutment Each abutment includes a base portion 21in the outer or which terminates at hingeline 22; an upright baclc portion lllih, the upper edge of which is connected to the inner edge of ledge lb, and upwardly inclined side portions lliFlc and d. it will be noted in FIG. 4 that the base portions Jil n is inclined downw ."dly relative to the adjacent portion ol the tr so that only the innermost edge of the base portion is in point or line contact with the portion lilo which is disposed between adjacent cells. The abutments function to {a} prevent overpivoting of the tiap lo when the tter moved to its upright um oi tin. im-

locking position and retain the flap in its locking position, (b) permit the'end limits of the flange carrying the locking ledges to be flexed inwardly as a cantilever a slight amount when finger pressure is exerted thereon so as to facilitate unlocking of the cover, and (c) reenforces the ledge surface L and thus,

minimize warpage and distortion of the ledge when subjected to extreme climatic conditions. It should be noted that the inclined side-portion 23d of each abutment engages only the inner edge of the ledge L; thus, the side portion in no way interferes with the interlocking engagement between the ledge surface L and the front wall 17 of the cover 24 as will hereinafter be described.

The cover front wall 17 is provided with a pair of elongated openings 24 and 25 which are disposed in vertical alignment with the corresponding locking ledges L of the flap when the cover is in its closed position. Each opening has the portion of the wall adjacent the lower edge 24a and 25a thereof offset inwardly so as to form a locking protuberance P. Edges 24a and 250 are disposed at approximately midheight of the cover front wall 17. Each edge extends abruptly inwardly from the front wall and, thus, provides an effective male lock component for the corresponding locking ledge surface L, see FIG. 4. It should be noted that the extent of inward projection of the protuberance P is less than that of the corresponding locking ledge L; thus, the backwall portion 23b of the abutment 23 in nowise interferes with the locking engagement between the protuberance P and the ledge surface L. Each protuberance is preferably inwardly curved and tapers downwardly from the edge 24a or 25a to portion 21a of the peripheral flange 21 delimiting the open bottom of the cover. Thus, by reason of such configuration, each protuberance P is highly resistant to deformation, notwithstanding that the carton is made from molded pulp and the remainder of the cover front wall is relatively resilient.

When the cover 14 is locked in a closed position with respect to the tray 11, a segment of the portion 15b of the locking flap 15 disposed above the ledge surface L is exposed within the corresponding front wall opening 24 or 2 5, see FIG. 5. While said segment is exposed within each opening, no part of the flap protrudes through the opening and outwardly from the exposed surface of the cover front wall. Thus, there is no outwardly extending button or lug which might be accidentally damaged or depressed, or which might interfere with stacking of loaded cartons.

In order to render the locking flap 15 more resistant to overpivoting when it is moved to its upright locking position, the flap may be provided with additional inwardly projecting abutments 26 and 27, see FIGS. 1 and 2. The additional abutments are interposed the abutments 23 and each is provided with a substantially flat surface 26a and 27a which is adapted to engage in surface-tosurface contact marginal portions of the tray upper edge flange 13 located between adjacent cells llb-c or llc-d forming the front row of cells in the tray section 1 1. It should be noted that the angular disposition of abutment surfaces 26a and 274 relative to abutment surfaces 23a is such that surfaces 26a and 27a will engage the marginal portions of the tray flange 13 prior to contact being made by the abutment surfaces 23a as the flap 15 is being pivoted to its locking position. The reason for this arrangement is to enable the lateral end portions of the flap to be manually flexed inwardly a sufficient amount so as to permit the cover wall protuberances to disengage the ledge surfaces L when the cover is to be opened. Thus, when unlocking the cover, the

segments of the flap portion 15b exposed in the cover apertures 24 and 25 are depressed by finger pressure causing the engaged segment and the ledge surface L to move inwardly which, in turn, causes the inner edge of the abutment surface 23a to penetrate a slight amount into the flange surface 13a. Inward movement of the flap segments is possible because the lateral end limits are not in contact with the articles accommodated in the adjacent cells. The cantilever flexure of the flap portion 15b and the ledge surface L as a unit occurs about an angularly disposed imaginary axis Z--Z shown in dotted lines in FIG. 2. For example, the flap end limits will flexure around and be substantially out of contact with an egg in the adjacent cell.

The inherent "fight back" of the flap 15 to bending coupled with the abutment contacts serve to resiliently hold the flap in a locking position against the interior surface of the cover front wall 17, when the latter is in its closed position, see F IG. 4. The flap 15, if desired, may be of sufficient height that it supportingly engages the underside of the cover top panel 16 when the cover is closed.

FIG. 6 shows a carton embodying a modified form of locking flap 115 wherein the outwardly disposed sidewall of each abutment 123 has been omitted. Thus, each abutment 123 includes a backwall portion 123b, one inclined sidewall portion 1230, and a base portion 1230. The upper edges of the abutment side and backwalls terminate at the inner edge of the locking ledge surface L in a manner as previously described with respect to abutments 23.

Thus, with either type of abutment 23 or 123, a substantial portion of the periphery of each locking ledge surface L is effectively reenforced and yet, neither type of abutment in nowise interferes with the locking engagement between the ledge surface L and the protuberance P, notwithstanding that the protuberance and ledge surface might be out of alignment. Because of the angular disposition of each locking ledge surface L with respect to the flap portion 15b, the front edge of the ledge surface is exceptionally rigid and thus, is capable of withstanding repeated opening and closing of the cover without causing rupture of the ledge surface.

in closing a loaded or partially loaded carton, either manually or by automatic equipment, the locking flap 15 is pivoted upwardly and rearwardly about hinge-line 22 until the abutments 26 and 27 engage corresponding portions of the upper surface of the tray section 11. While the flap 15 is retained in such a position, the cover section 14 is pivoted, either manually or mechanically, about the hinge-line 19 connecting the rear walls of the cover and traysections until said cover section assumes a superposed, overlying position with respect to the open top of the tray section. As the cover section is moved to its closed position, the cover front wall telescopes over the flap and the protuberances P carried by the cover front wall engage the portions 15b of the flap causing the flap to flex inwardly a slight amount permitting the cover wall protuberances to slide past the front edges of the ledge surfaces whereupon the protuberances will snap into locking engagement with the ledge surfaces L.

As aforementioned, to unlock the carton, requires only the flap portion 15b exposed in the cover wall apertures to be manually depressed slightly to disengage the protuberances from the ledge surfaces whereupon the cover section may be readily swung to its fully opened position exposing the contents of the carton.

While the improved lock construction has been described in relation to an egg carton, it is to be understood, of course, that it is not intended to be limited thereto. An egg carton was selected merely to facilitate understanding of the invention. If desired, the cover and tray sections need not be hingedly interconnected but instead the cover section may be wholly separate from the tray section. in such an arrangement, a locking flap would also be hingedly connected to the elongated rear upper edge as well as the front upper edge of the tray section. The rear wall of the cover section, in turn, would be provided with openings and protuberances in the same manner as in the case of the cover front wall. The tray section may be noncellular or both the cover and tray sections may be cellular without adversely affecting the improved lock construction. The term molded hereinafter utilized in the claims is intended to cover thermoformirrg, vacuum-forming, and injection molding.

We claim:

1. A molded carton comprising a tray having upwardly extending sides delimiting an open top, said tray having a plurality of cells formed therein and arranged in a row adjacent one side of the open top; a cover having a top delimited by depending walls, said cover being movable into and out of an overlying closed position with respect to said tray open top; an elongated locking ilap hingedly connected to the one side of said tray open top and having the lateral end limits thereof biased outwardly to resiliently engage the interior surface of a depending cover wail, said flap, when in locking position, being disposed upright and in telescoping relation behind one depending wall of said cover when the latter is in said closed position, said flap having the opposite lateral end limits thereof in substantial registration with portions of the tray disposed intermediate adjacent cells of the row, said flap being provided with inwardly extending abutments disposed adjacent the flap hinge for contacting adjacent tray portions and retaining said flap in loclting position, each lateral end limit of l5 said flap being provided with a substantially rigid elongated locking ledge disposed intermediate the ilap hinge and the flap edge opposite thereto and in substantial registration with one of said portions of the tray intermediate adjacent cells of the row, one end of said ledge being open and terminating at the flap lateral end linnit, said ledge having a substantially flat surface projecting inwardly at an abrupt angle into the interior of the closed carton; the one depending wall of said cover being resilient and provided with inwardly extending protuberances spaced downwardly from the cover top, each protuberance having an upper lip for loclringly engaging a corresponding ledge written when said cover is in said closed position, the inward projection of said locking ledge surfaces being greater than the inward projection of said locking lips, said flap in the region of said end limits having cantilever flexure greater than the inward projection of said lips.

2. T he molded carton of claim it wherein said cover one depending wall is provided with openings disposed above said locking lips and in substantial vertical alignment therewith, a portion of the flap being exposed within, but behind, each opening when said cover is closed, said exposed flap portions being adapted to be manually depressed to effect unlocking of the closed cover.

3. The molded carton of claim Z wherein said tlap tllllllrnents include first ahutinents disposed in vertical alignntcnt beneath said locking lips, and second abntrncnts r termediate said first allotments, all oi" said abutment aging portions of said tray open top disposed intermediate ad acent cells of the row.

d. The molded carton of claim 3 wherein each first abutment includes a first segment extending inwardly at an abrupt angle from said flap hinge and being adapted to overlie and engage a portion of the tray open top disposed internrc e adjacent cells, a second segment crrtending upwardly at an abrupt angle from the inner end oi said first a W cm and con nesting with the inner edge ot said inching l and a third segment spaced endwise from end lirnit o r and in terconnecting corresponding side c lltll t and second segments and an adjacent edge of raid inciting ledge.

5s. The molded carton of claim 3 wherein said second abut ments are adapted to be in substantially taccdotace contact with portions of said tray open top and said first abutrnents are adapted to he in substantial line contact with the other par tions of said tray open top.

6. The molded carton of claim 55 wherein said second abutments being provided with base surfiaces which engage portions of the tray open top prior to said i'ir hutntents ntalting line contact with adjacent portions when said loclring lie is moved to an upright position whereby said cover wall can assume a telescoping relation therewith.

7. The molded carton of claim a wherein the loclring ledge surface, the portion of the flap disposed thcreabove, and the first abutment in substantial vertical alignment with said ledge surface, being flexible as a unit relative to the remainder of said flap about an axis obliquely disposed with respect to the hinge aids of said flap to effect locking and unlocking of said cover wall protuberance with r spr ct go said ledge surface. 

1. A molded carton comprising a tray having upwardly extending sides delimiting an open top, said tray having a plurality of cells formed therein and arranged in a row adjacent one side of the open top; a cover having a top delimited by depending walls, said cover being movable into and out of an overlying closed position with respect to said tray open top; an elongated locking flap hingedly connected to the one side of said tray open top and having the lateral end limits thereof biased outwardly to resiliently engage the interior surface of a depending cover wall, said flap, when in locking position, being disposed upright and in telescoping relation behind one depending wall of said cover when the latter is in said closed position, said flap having the opposite lateral end limits thereof in substantial registration with portions of the tray disposed intermediate adjacent cells of the row, said flap being provided with inwardly extending abutments disposed adjacent the flap hinge for contacting adjacent tray portions and retaining said flap in locking position, each lateral end limit of said flap being provided with a substantially rigid elongated locking ledge disposed intermediate the flap hinge and the flap edge opposite thereto and in substantial registration with one of said portions of the tray intermediate adjacent cells of the row, one end of said ledge being open and terminating at the flap lateral end limit, said ledge having a substantially flat surface projecting inwardly at an abrupt angle into the interior of the closed carton; the one depending wall of said cover being resilient and provided with inwardly extending protuberances spaced downwardly from the cover top, each protuberance having an upper lip for lockingly engaging a corresponding ledge surface when said cover is in said closed position, the inward projection of said locking ledge surfaces being greater than the inward projection of said locking lips, said flap in the region of said end limits having cantilever flexure greater than the inward projection of said lips.
 2. The molded carton of claim 1 wherein said coveR one depending wall is provided with openings disposed above said locking lips and in substantial vertical alignment therewith, a portion of the flap being exposed within, but behind, each opening when said cover is closed, said exposed flap portions being adapted to be manually depressed to effect unlocking of the closed cover.
 3. The molded carton of claim 2 wherein said flap abutments include first abutments disposed in vertical alignment beneath said locking lips, and second abutments arranged intermediate said first abutments, all of said abutments engaging portions of said tray open top disposed intermediate adjacent cells of the row.
 4. The molded carton of claim 3 wherein each first abutment includes a first segment extending inwardly at an abrupt angle from said flap hinge and being adapted to overlie and engage a portion of the tray open top disposed intermediate adjacent cells, a second segment extending upwardly at an abrupt angle from the inner end of said first segment and connecting with the inner edge of said locking ledge, and a third segment spaced endwise from the end limit of said flap and interconnecting corresponding side edges of said first and second segments and an adjacent end edge of said locking ledge.
 5. The molded carton of claim 3 wherein said second abutments are adapted to be in substantially face-to-face contact with portions of said tray open top and said first abutments are adapted to be in substantial line contact with the other portions of said tray open top.
 6. The molded carton of claim 5 wherein said second abutments being provided with base surfaces which engage said portions of the tray open top prior to said first abutments making line contact with adjacent portions when said locking flap is moved to an upright position whereby said cover wall can assume a telescoping relation therewith.
 7. The molded carton of claim 6 wherein the locking ledge surface, the portion of the flap disposed thereabove, and the first abutment in substantial vertical alignment with said ledge surface, being flexible as a unit relative to the remainder of said flap about an axis obliquely disposed with respect to the hinge axis of said flap to effect locking and unlocking of said cover wall protuberance with respect to said ledge surface. 